Traditional mayonnaise is an oil-in-water type emulsion comprising vegetable oil (70-80%), egg yolk (5-8%), salt, vinegar (to achieve a pH of the water phase of less than 4.2 to be considered an acid stable food), mustard, and optionally sugar, pepper and herbs. The oil is generally present in mayonnaise as a dispersed phase with an average droplet size of 3-8 μm. Because of the droplet size and the high amount of dispersed phase, mayonnaise contains a very close packing of oil droplets. The close packing of oil droplets in combination with the very thin layer of aqueous phase separating said droplets results in a mayonnaise that exhibits a very desirable rheology that is perceived by consumers as a creamy thickness.
Mayonnaise typically has a specific density of about 0.9 g/cm3. To keep the emulsion stable it is common practice in the field of mayonnaise to employ egg yolk as an emulsifying agent, although other emulsifiers, such lecithin, propylene glycol esters, alginates and vegetable gums have also been proposed.
There is an ever-increasing demand for mayonnaise-type products having a lower content of oil. However, the lowering of the oil content of a standard mayonnaise-type formulation will result in a less dense packing of the oil droplets within the continuous aqueous phase. As a result, the thickness or viscosity of the emulsion will decrease dramatically. Thus, a reduced fat mayonnaise of inferior quality is obtained, e.g. a mayonnaise that is not spoonable. In fact if the oil phase is reduced below the critical packing level (˜65% w/w), a conventional mayonnaise will become pourable.
It has also been proposed in the prior art to reduce the oil content of mayonnaise by preparing an aerated mayonnaise product. U.S. Pat. No. 3,728,133, for instance, discloses mayonnaise foams comprising, as foaming agents, monoglycerides and hydroxy fatty acid ester of a glyceride.
U.S. Pat. No. 4,578,278 describes an aerated mayonnaise type foodstuff comprising a foam of micro bubbles of gas or air in an oil-in-water emulsion of oil, water, egg yolk, vinegar, seasoning, a gelifying stabilizer and coagulated whipped egg white. The gelifying agent is suitably selected from the group consisting of gelatine, pectin, alginates, carrageenan, agar, carob polysaccharides and starch.
An important disadvantage of the aforementioned foamed mayonnaise products resides in the fact that the advocated use of additives may not be allowed in products labelled as “mayonnaise” by national regulations. Furthermore, consumers increasingly object to the use of such additives to foodstuffs.
Hence, there is a need for aerated mayonnaise products that can easily be produced at a high overrun, whose foam structure remains stable during shelf life and which products are further characterised in that they do not contain any additives that are not conventionally used in mayonnaise.